Biomedical subjects

Liane Kaufmann

Publications and source records attributed to Liane Kaufmann.

5 recordsLinked to original sources

PubMed2004

Deficient arithmetic fact retrieval--storage or access problem? A case study.

This paper aims at clarifying the nature of fact retrieval difficulties in an 18-year-old young man (MO) who exhibited a puzzling pattern of developmental dyscalculia. Contrasting performance on explicit (production and verification tasks) and implicit (priming) tasks we observed poor overt retrieval of addition and multiplication facts, classical interference effects in verification tasks and inconsistency of error patterns. Hence, MO's performance pattern is suggestive of the existence of a partly stored network of facts (reflecting imperfect storage), but is also compatible with an access deficit according to Warrington and Cipolotti's [Brain 119 (1996) 611] criteria for distinguishing access and storage deficits in dysphasic patients. Furthermore, while MO displayed interference effects in verification tasks, he did not show automatic access to arithmetic facts in implicit tasks. Finally, similar to the findings of Roussel, Fayol, and Barrouillet [European Journal of Cognitive Psychology 14(1) (2002) 61] on normal subjects, MO's performance pattern is suggestive of the existence of differential processing mechanisms for addition and multiplication facts. We propose a unifying mechanism, namely a deficit of the central executive of working memory (WM), that accounts both for the constitution of a fuzzy network of fact representations, and for an access deficit modulated by attentional demands as required in explicit/implicit task paradigms. Overall, our results clearly provide evidence that even in (a developmental) case of a non-perfect network of memory representations (e.g. [Journal of Experimental Psychology: General 117 (1988) 258]), interference effects might be observed. Future studies thus need to be cautious before concluding that interference effects prove the existence of a well-established associative memory network of arithmetic facts.

Adolescent↗

PubMed2004

On the development of the mental number line: more, less, or never holistic with increasing age?

Magnitude is assumed to be represented along a holistic mental number line in adults. However, the authors recently observed a unit-decade compatibility effect for 2-digit numbers that is inconsistent with this "holisticness" assumption (H.-C. Nuerk, U. Weger, & K. Willmes, 2001). This study used the compatibility effect to examine whether the mental number line representation of magnitude changes toward greater or less holisticness in children from Grades 2-5. The results indicate that decades and units of 2-digit numbers are processed separately rather than holistically from Grade 2 on. However, this separate processing seems to develop from a more sequential (left-to-right) to a more parallel processing mode. Moreover, children may use different strategies depending on task demands. The results are interpreted in the framework of Siegler's overlapping waves model.

Child↗

PubMed2002

More evidence for the role of the central executive in retrieving arithmetic facts - a case study of severe developmental dyscalculia.

It has been shown repeatedly that simple mental calculation depends not only on long-term memory (LTM) representations but also on working memory (WM) resources. The study describes the performance of an adolescent, M.O., exhibiting severe developmental dyscalculia, but literacy problems as well. Despite having relatively preserved procedural skills, M.O. exhibited outstanding difficulties in retrieving arithmetic facts which are most pronounced on multiplication and division problems. Interestingly, his performance on non-numerical memory tests was within average (independent of modality), while his attention span was just below average. Testing the different components of WM, the results emphasize the major role of the central executive in solving simple mental calculations.

Adolescent↗

PubMedDate not supplied

Evaluation of a numeracy intervention program focusing on basic numerical knowledge and conceptual knowledge: a pilot study.

The preliminary results of this study suggested that children with developmental dyscalculia benefit from a numeracy intervention program that focuses on basic numerical knowledge and conceptual knowledge. All children in the experimental group showed considerable and partly significant performance increases on all calculation components. Six children with developmental dyscalculia were trained individually and in small-group settings for a relatively short duration (one school semester). We argue that the positive intervention effects to a large extent are attributable to the explicit teaching of numerical domains that often have been found to be neglected in school mathematics.

Child↗

PubMedDate not supplied

About the relationship between basic numerical processing and arithmetics in early Alzheimer's disease--a follow-up study.

We studied the relationship between basic numerical knowledge and arithmetics (facts and procedures) in early Alzheimer's Disease (AD). In most patients, basic numerical knowledge was found to be preserved, as reflected by low error rates, distance effect in number comparison, and subitizing in naming numerosities. However, within arithmetics, AD patients exhibited decreased fact and procedural knowledge. Interestingly, double dissociations were found not only between facts and procedures but also between basic numerical knowledge and arithmetics. Thus, our results suggest that basic numerical knowledge need not be a prerequisite for the maintenance of arithmetics, but rather corroborate calculation models that postulate the functional independence of its components. Further, we found patient specific error types which might serve to identify early AD. The follow-up about one year later indicated significant qualitative, but only marginal quantitative performance changes.

Age Factors↗